Creating an SHA1 Hash in a text-field from an imput text-field

I have to convert i.e. 'QEX\JohnKwachtwoord' to 'abb4a8f6dbebdeb71f0f63f0cba7b8ee9e6cc67b'
I tried to use System.Security.Cryptography.HashAlgorithm.'mscorlib, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089'
but that gives me an Uppercase text like: 1CEE2F310C53CCA7CA43527AC59CE23D29A088F2
Does anyone have a solution?